FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: bn69stang on December 22, 2014, 08:33:31 PM
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Hopefully this year , sooner than later i will be looking to purchase a 427 block and i thought i would poll you guy s on iron or aluminum , i am wanting at least 500 inchs , all your thoughts and input will appreciated .. Bud
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i have one. it is a pond 482 making 705hp, i like the motor but a lot of maching money to be spent getting up to spec. all these aftermarket aluminum blocks are just i will call it rough machined. also this motor takes quite awhile to get up to engine temp. i had barry R at survival build it. i guesss i should ask is what are you gonna do with it?
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For the street.........one word and three letters............iron BBM. Can't go wrong at $3295 plus frt. REALLY nice blocks.
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Most aluminum blocks only go to 4.310 with standard sleeves, but there are optional bore sleeves that are available to go 4.440" but cost more initially. The new BBM block in iron can go 4.440" and still has good sonic numbers. If you are looking for cubic inches and less cost, then the iron block is the way to go. It is more stable, and easier to get all your clearances to stay in tolerance. I have both, and the real advantage of aluminum is weight--118# vs 250#. Joe-JDC.
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i agree with the iron block for the street. but one thing i did do when i got that pond all aluminum block was i wieghed it with a factory 390 block and it was 93 pounds lighter, that was just the blocks and nothing else. i new it was lighter but i was not expecting that much. if i had to do it again i wouldnt build another aluminum motor. it takes a lot of $$$$$$$$.
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i didnt check into the bbm block until tonite. to be honest if i was to build another aluminum motor that would be the one i would buy. it is much nicer piece as opposed to my pond block, has better main caps. plus it is quite a bit cheaper than the pond and shelby block by quite a bit.
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I am using a Shelby alu block on the street. My main reason for this choice was to reduce weight in the front of my Mustang but also because I wanted lotsa cubes so I got their "Big Bore" opion which is 4.375. The stroke is also 4.375 so I got 527 cubes.
Barry R built this engine for me so I cannot tell you what and how much machining was involved.
I love the torque. Very streetable.
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That BBM block looks nice, alright, but at 270 pounds its just too heavy. I like aluminum blocks because you can save 100 pounds over a factory cast iron block (more than that over an aftermarket cast iron block), plus with the replaceable sleeves if you have any engine damage in the bores you can just pop in a new sleeve. To say nothing, of course, of the repairability of aluminum vs. cast iron. If my big SOHC engine had been a cast iron block, I can't imagine it would have been fixable. It is true, though, that the cast iron blocks are more stable; every time I pull apart an aluminum block it needs an align hone to get it back right again. And the aluminum blocks are more expensive...
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The weight comes down quite a bit when boring out to 4.375 up on the iron. I thought I saw my shipping invoice with pallet read 250# for a new iron BBM block. Now I will have to weigh it to get peace of mind. Maybe start at 4.390" for first build. Joe-JDC.
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I asked Doug at BBM about the weight a couple months ago. He told me 250 pounds. I don't have one to weigh, but it would be interesting to know the exact weight. Maybe the 270# Jay referenced, was a small bore (428) block? Or possibly a shipping weight with pallet? The small bore blocks have a 4.180 bore, for 428 stock and super stock class engines mainly. The cylinders walls are real thick... like well over .400 on a 4.245 bore as delivered, so even more on a small bore. Also I believe it is solid below the freeze plugs, similar to a "short fill", so some weight there, and the thick decks, massive caps... it all adds up. I think the Pond iron and side oiler garage are all around 250 or so as well.
Joe is correct that blocks do shed some weight when boring chips hit the floor. The A460 block is real heavy and when they bore it .125 over it loses some weight big time. I don't know if I would go 4.390 right away, without checking ring availability anyway. I think maybe around 4.375 as you can get a nice ring pack for several bore sizes between 4.375 and 4.400, for future rebuilds, availability can get real spotty after that. Supposedly the max bore is 4.440, but I would start worrying about head gasket sealing between cylinder at that size maybe?
One other thing is, iron blocks will make more power and can go bigger. You won't find any aluminum blocks in Pro Stock, most Comp eliminator engines as well, where budget is not an issue, HP is.
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A 4.390" would be a .030" over 460, so I'd say rings are easy to find. A 4.400" bore is easy as well.
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I asked Doug at BBM about the weight a couple months ago. He told me 250 pounds. I don't have one to weigh, but it would be interesting to know the exact weight. Maybe the 270# Jay referenced, was a small bore (428) block? Or possibly a shipping weight with pallet?
One other thing is, iron blocks will make more power and can go bigger. You won't find any aluminum blocks in Pro Stock, most Comp eliminator engines as well, where budget is not an issue, HP is.
I never weighed a BBM block, and have never seen one in person; somebody who got one just gave me that number. As far as cast iron vs. aluminum goes for power, I've been hearing that for years but never seen anything definitive on it. I suppose that would be a tough back to back comparison to make, but I sure would like to see it. It would have to be due to better ring seal on the cast iron block, right? And for most people there would have to be enough power in the cast iron block to offset the 100 additional pounds it adds to the car. That's a lot of power. Color me just a little skeptical on that one...
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A 4.390" would be a .030" over 460, so I'd say rings are easy to find. A 4.400" bore is easy as well.
Well I am not talking about normal 1/16" ring availability etc. but "thin" steel rings like .043, 1MM, or even .7mm, .030 etc. (if you got the coin). I'll be honest, I haven't looked into it real deep... but just wanted to mention that it is a good idea to check ring pack availability before ordering pistons and boring blocks I guess. It will be a custom piston anyway, so might as well get a custom ring pack (first).
I know for a 60 over 460 ring, there aren't many options, but at .080 over there are plenty (4.420 and 4.440).
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That is what the Pro Stock guys say, is more power from ring seal. They are bore space limited and go as big as they can and a short stroke, so that may come into play as well (wall thickness). I imagine it is only a small HP number, but they are after every little bit at that level. Same in Nascar (iron blocks) but that might be a rules thing, not sure.
I would like to take 100# off my front end, but the extra $1200-1500 additional cost (over a new iron block) would kind of hurt the wallet. I am still running and old beat up 65 FORD center oiler, filled with "grout", so it is a little heavy as well. I have to run an adjustable restrictor under the carb to slow mine down, to be legal at 10.00 seconds. I'm not ready to go through all the NHRA hoops and costs to run in the 9's, but still have done it at several tracks during test-n-tune and/or qualifying, never during eliminations or I'd get the "boot" for sure.
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BBM 427 at 4.245 bore weights 257 lbs with caps (caps 20 lbs)
BBM 428 at 4.170 bore weights 262 lbs with caps (caps 20 lbs)
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Thanks for all the great feed back guy s , I will really put thought into this and i have seen in person both iron and aluminum BBM blocks at blue oval performance , and i can say the casting and machining look great . the great thing about this forum is the knowledge and years of experience , and it greatly appreciated and used . And again this will be street car , but cubes rule .. Bud
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The BBM site claims 250 pounds for their iron block, which does sound heavy, but what does a factory 427 SO block weigh at standard bore, with a fill or Hard Block? I agree that 120 lbs or so off the noise would be nice, but an extra $1200. to get it kinda hurts. As for alum vs iron blocks for HP, my buddy has built a number of B1 headed MoPar big blocks and Hemis for a local racer (with too much $$$$!), and 1 big inch wedge made over 800 HP with a MoPar Performance iron block, and they later swapped all the internals into an aftermarket aluminum block, and it lost about 40 HP.
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My new Sideoiler Garage block weighs 250lbs on my scales. That's unbored at 4.23 I believe, so some could be lost in a big overbore. That's about 50lbs heavier than my stock sideoiler block, but there's a LOT of beef added with siamesed bores clear to each bulkhead, .750 thick decks, webbing across the lifter valley (which could be removed), and solid main saddles with big billet caps.
From what I've seen of the BBM blocks, they are not siamesed between the end bores and the bulkheads, so to be about 7lbs heavier they must have some really thick casting elsewhere.
If you go with aluminum heads, water pump, pulleys etc, the weight should easily come back down to about what a stock FE weighs. Throw in a lighter modern intake, aluminum flywheel, cut down crank, lightweight valves (it all adds up) etc, and I'm sure you would end up lighter than a stock FE. Just something to think about.
I'd love to go aluminum, but the cost is prohibitive for average guys. Sorry, Jay, you're not average ;) In the end I think an iron block is more of a long term piece as long as you don't blow holes through the sides. You can start small and get probably 8-10 overbores before you have to consider sleeving. Of course if you don't punch a hole in it within that time, you just ain't trying hard enough ;D ;D
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Sideoiler blocks weigh in at +/-260 on my scale here. Pretty close to other numbers.
The additional web across the deck that splits the front & rear water opening adds some strength to that wall - a nice feature. They also have a billet main cap, but without the extra metal hanging below the fasteners. You could make some sort of a case for the extra arch between the fasteners (its a bit of a "reach" considering the generous cross sections already there on the flat caps used by Pond and SG), but the piece between the fastener and the pan rail is simply a machining artifact that can be removed without any possible impact.
We've eliminated the pull thread in the center of the caps - just seemed like the wrong place to have a threaded hole. We are considering putting two or three 9/16 threads just under the fastener spotface (an area under a compressive load) as a grab for a slide hammer for easier removal. No decision yet on that.
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From what I can tell, there has to be about 30 hp difference between a good modern iron block and a Shelby aluminium. I have had two almost identical engines on the same dyno..........the iron made 920 hp, and with bigger valves and about 20 more cfrm through the middle of the lift, the aluminium engine made 900 hp with a top-of-the-line vacuum pump. There was probably another 20 hp in the aluminium engine due to exhaust flange mismatch with my dyno headers (have checked it before), but the vacuum pump is worth something on the aluminium block, and the better head flow is also. I think an iron block with the vac pump would show me 950 hp on that combo, and the alum 920 hp if I built a set of headers that fit the exhaust port correctly. My opinion is 30 hp iron vs. aluminium with everything else a constant..............but that is at the 900+ power level. In a 600 to 700 hp street engine, it is not that much, speaking linear terms, but there are other things to consider on the street. The lifters will bleed more when hot, and the mains need to be "adjusted" for expansion on the aluminium........on the street or the track. Power vs. weight, it is ALMOST a wash for a drag car. The power would almost be offset (within a few hundredths) by the weight difference, but the car should "work" better with the weight off the nose. In a road racer, with a dry sump, I say aluminium all the way. On the highway, I lean toward the iron from the long term, trouble free use aspect. JMO.
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I agree on the iron vs aluminum power deal.
While I have not got any hard evidence (most comparable ones I've done seem really close), I had a local contact that does a lot of very similar oval track builds. He claimed a clear 20HP advantage on iron 600HP deals. In his world that was worth the weight.
Can't speak for the BBM, but there are weight savings opportunities on the Pond, Genesis, and Sideoiler blocks. Won't get you down to OE levels - but still worth looking at if you're trying to get closer. The ribs in the valley can "go away" on iron, overboring to a larger size will obviously knock a bit off the scale. You could mill a fair amount off inside above the pan rails - they added metal there cuz everybody always sees the windowed 427s - but that was never the block's fault.
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All the bores punched out 1/8" is under 10 lbs. Probably a couple pounds more in those valley ribs but it's doubtful you can get it within 25 lbs of the factory block.
Has Pond made any of the graphite blocks?
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I have limited experience with big power cast iron blocks, but I do have one comparison that is pretty close to apples to apples. The 511" Shelby block FE that I took to Drag Week in 2005 made 706 horsepower on the dyno before it went into the car. A couple of years later, when I was building my dyno mules for the testing for my book, I used many of the same components over again on my 492" stroker engine, which used a factory cast iron block. Same ported Victor intake, same Dominator carb, same set of ported Edelbrock heads, same Comp roller cam, same headers, etc. Compression ratio was also the same, although the pistons were different because the bores were different. That 492" engine peaked at 675 HP with that stuff on it. The Shelby block engine made 1.38 HP per cube, and the factory sideoiler block engine made 1.37 HP per cube. Now in fairness the walls on the factory 427 block were thin because it was bored .060", but I don't think the extra .030" bore would have cost 20 or 30 HP. But who is to say for sure.
I'm not going to be totally convinced on this until I see a real back to back comparison, with all components the same. It'll probably never happen...
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Has Pond made any of the graphite blocks?
I talked to Robert about those compacted graphite blocks a couple years back, and he sounded like he had abandoned the project...
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I'm not going to be totally convinced on this until I see a real back to back comparison, with all components the same. It'll probably never happen...
Hmmmmmm..., Hey Jay, ready to write a new book? How about :"The Great FE Block Comparo", plus you could update the manifold tests by adding a section using your adapter and all the various 351C intakes on your 3 different engines from the previous book. I guess asking for it to be finished in time for Christmas is un realisyic, eh? :o :D
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Another book LOL! I'll tell you, Rory, I had plans to write "The Great FE Cam and Head Comparo" at one point, before I actually got going on writing my intake book. But that book was a whole lot of work, and basically took me out of racing for a full year in order to get it done. So I'm postponing any future books until I have more time, maybe when I retire or something...
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Retire? Say it ain't so Jay....you have miles & miles of FE work yet to go!
LOL!
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Just throwing this out there...
The reason many aftermarket blocks are heavy is that it is easier to cast heavier walls than thin walls. The OEM factory can throw lots more manpower at a casting project and can afford to throw away a bunch of blocks while troubleshooting the casting process. The factory has a vested interest in keeping the blocks light partly because more metal is more money spread out over thousands of blocks means big money. And they need to keep the vehicle weights within reason for fuel economy etc. The big OEM's can afford extensive FEA and well as iterative destructive testing (keep adding weight until the blocks stop blowing apart).
The much smaller aftermarket guys just have to take an educated guess where to add metal to strengthen these old design blocks. A lot of the extra material goes to the water jacket areas where its really not needed. There was one shop in Michigan that had a CNC program to cut away the outside material off of 385 series aftermarket blocks, they were wacking off 40-50 lbs approximately.
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Retirement is for old people , none of are there yet right ? , anyway Jay more books would be useful lol ... Bud
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So far the iron block seems to be more popular for street , all i know is i ll be able buy only one , not one of each lol darn the budget . Bud
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Another reason the big manufacturers build things as light as possible is cost over the long production run. Say you add 5 pounds to an aluminum block and make a million of them over a five year span. That's 5,000,000 pounds of aluminum. Not sure what aluminum is going for but that adds up quick. All adds or takes away to the bottom line.